1. Field of the Invention
The present invention relates to an improvement of a flat core brushless motor suitable for driving a spindle or a pickup used for a portable mini disk apparatus.
2. Description of the Related Art
A conventional flat core brushless spindle motor used for a portable mini disk apparatus is shown in FIG. 5. That is, a brass bearing holder H is installed at a stator base B. A stator core C is formed by winding an armature coil N around a plurality of protruding poles, and is installed at the outer circumferential surface of the bearing holder H. A bearing J is installed inside the bearing holder H. A rotor R having a magnet M which is installed in a magnet holder Y facing the stator core C with a gap, is supported through a shaft S rotatably inserted in the bearing J. In the drawing, T denotes a turntable on which media is installed, which is integrally formed with the rotor R.
However, the flat spindle motor having the above structure is restricted in being made thinner by an expanded portion of the armature coil N wound around the protruding poles. Thus, the expanded portion of the armature coil is usually compressed and impregnated. Nevertheless, there is a problem of occasional disconnection or shorting of lines.
Also, when the expanded portion of the armature coil is not compressed and impregnated, the number of accumulated thickness units of a core must be reduced and thus the property of the motor is sacrificed. To solve this problem, a part of the core has an L shape. That is, a blade portion of the core is folded in an axial direction. However, this increases the manufacturing cost.
To solve the above problems, it is an objective of the present invention to provide a flat core brushless motor which can be made thin without compressing and reducing the expanded portion of an armature coil, to help reduce the effect of the stator base on the overall thickness of the motor, and without reducing the number of accumulated thickness units of a core, so that the properties of a motor are not sacrificed.
Accordingly, to achieve the above objective, there is provided a flat type core brushless motor formed by installing a stator which is made by winding an armature coil around each of a plurality of protruding poles at a stator base, in which a concave portion for escape of the armature coil is installed at the stator base.
It is preferred in the present invention that the concave portion for escape of the armature coil is a hole arranged at a circuit board attached to the stator base.
It is preferred in the present invention that the concave portion for escape of the armature coil is a hole arranged at a circuit board attached to the stator base and a hole installed at the stator base thereunder.
It is preferred in the present invention that the concave portion for escape of the armature coil is a hole arranged at a circuit board attached to the stator base and a hole installed at the stator base thereunder.
It is preferred in the present invention that the circuit board is formed of a thin flexible sheet to cover the edge of the hole formed in the stator base.
It is preferred in the present invention that a plurality of supports, which are lifted from the stator base by pressing processing, are used as a means for installing the stator and simultaneously a hole formed by the press processing for lifting the supports is used as part of the concave portion for escape of the armature coil.
It is preferred in the present invention that a rotation support portion is arranged inside the supports.